MainLandQuestion

package org.example;

import java.util.LinkedList;
import java.util.Queue;

public class MainLandQuestion {

    private  int[][] directions={{-1,0},{1,0},{0,-1},{0,1}};

    public static  void   main(String[] args){
        MainLandQuestion mainLandBFS=new MainLandQuestion();
        char[][] grid1 = {
                {'1', '1', '0', '0', '0'},
                {'1', '1', '0', '0', '0'},
                {'0', '0', '1', '0', '0'},
                {'0', '0', '0', '1', '1'}
        };
        System.out.println(mainLandBFS.resolve(grid1));
    }

    public int resolve(char[][]  grid){
        int rows=grid.length;
        int cols=grid[0].length;
        int  mainlandCount=0;
        boolean[][]  visited=new boolean[rows][cols];
        for(int i=0;i<rows;i++){
            for(int j=0;j<cols;j++){
             if(!visited[i][j]&&grid[i][j]=='1'){
                 mainlandCount+=1;
                 bfs(grid,i,j,visited);
             }
            }
        }
        return  mainlandCount;
    }

    /**
     * 深度优先遍历图
     * @param grid
     * @param row
     * @param col
     * @param visited
     */
    public void  bfs(char[][] grid,int row,int col,boolean[][] visited){
      int rows=grid.length;
      int cols=grid[0].length;
      Queue<int[]>  list=new LinkedList<>();
      list.offer(new int[]{row,col});
      while (!list.isEmpty()){
          int[] current=list.poll();
          int currentRow=current[0];
          int currentCol=current[1];
          for(int[]  direction:directions){
              int nextNodeRow=direction[0]+currentRow;
              int nextNodeCol=direction[1]+currentCol;
              if(nextNodeRow>=0&&nextNodeRow<rows&&nextNodeCol>=0&&nextNodeCol<cols&&grid[nextNodeRow][nextNodeCol]=='1'&&visited[nextNodeRow][nextNodeCol]==false){
                  list.add(new int[]{nextNodeRow,nextNodeCol});
                  visited[nextNodeRow][nextNodeCol]=true;
              }
          }

      }
    }

    /**
     * 深度优先遍历图
     * @param grid
     * @param row
     * @param col
     */
    public void  dfs(char[][] grid, int row, int col) {
        int m = grid.length;
        int n = grid[0].length;
        if (row < 0 || row >= m || col < 0 || col >= n || grid[row][col] == '0') {
            return;
        }
        grid[row][col] = '0';
        dfs(grid, row - 1, col);
        dfs(grid, row + 1, col);
        dfs(grid, row, col - 1);
        dfs(grid, row, col + 1);
    }
}